1. Field
The following description relates to a mobile communication system, and more particularly, to a configuration and procedures of a next-generation mobile communication network using link layer routing.
2. Description of the Related Art
A 3rd generation partnership project (3GPP) mobile communication network is based on a long term evolution (LTE) technology which relates to a wireless communication and an evolved packet core (EPC) technology which relates to a core network.
FIG. 1 is a diagram illustrating a configuration of a 4th generation mobile communication network. Referring to FIG. 1, the 3GPP mobile communication network is based on LTE for a wireless network and an EPC for a core network.
The EPC consists of a serving gateway (S-GW) for packet transfer between 3GPP-based wireless technologies; a packet data network gateway (P-GW) for packet transfer in association with non-3GPP-based wireless technologies, and a mobility management entity (MME) for supporting mobility between LTE wireless technologies.
In addition, the EPC basically utilizes an Internet protocol (IP) network technology, and largely uses a general packet radio service (GPRS) tunneling protocol (GTP) tunnel between a P-GW and an S-GW for packet transfer and mobility management on a core network.
However, as data traffic is exploding, the aforementioned 4th generation mobile communication network has the following problems.
First, according to GTP, IP packets are encapsulated, which requires additional headers, such as an external IP header, a UDP header, and a GTP header. Accordingly, 40 to 60-byte overhead is incurred in the initial IP packet, which may result in degradation of communication efficiency of a mobile communication network.
Second, the P-GW acts as a terminal end of the GTP tunnel, and if a host is moved and an S-GW is thus changed, a new GTP tunnel to a new S-GW needs to be established, which may lead to performance degradation during handover.
Third, because the P-GW acts as an anchor for all packet transfers, any packet transfer paths need to pass the P-GW even when a transmission host is in proximity, and this may cause path inefficiency and an increase in unnecessary traffic.
Fourth, since traffic concentration on the P-GW is caused because of the same reasons as the third problem, a large-capacity, expensive P-GW is required, and when the P-GW is out of order, it is impossible to transfer packets throughout the whole network and unnecessary traffic may be produced within the network.
To address the aforementioned problems, a new method, named ultra-flat architecture (UFA), has been suggested to design a flat mobile communication network without a central anchor.
FIG. 2 is a diagram illustrating a configuration of an evolved flat-mobile communication network.
Referring to FIG. 2, in the flat next-generation mobile communication network, most of network functionality is distributed to a base station side, such that access nodes (ANs) replace some of features that have been previously performed by an MME, an S-GW, and a P-GW, as well as providing wireless connectivity.
However, such a flat architecture is basically based on IP networking technologies in accordance with All-IP network paradigm, and still has limitations inherent in the IP networking technologies.
First, a great amount of cost is required to configure an IP network and establish relevant settings of a router to accord with the architecture, and to change the network architecture, if any.
Second, because an IP address is used as a locator for routing, as well as an identifier of an ongoing session, it is required to obtain a new IP address when a host is handed over, and this may cause the disconnection of the ongoing session.
To solve the aforementioned problem, some technologies to perform routing not at layer 3 but at a link layer, which is required for packet transfer between multi-hops have been suggested.
However, these technologies are only dealing with a network of limited scale, such as a campus network or a data center, and there are not yet provided any technologies that can be applied to a large scale network, such as a mobile communication network.